First-principles approach to thin superconducting slabs and heterostructures

TL;DR

This paper introduces a first-principles computational method to study superconducting thin films and heterostructures, focusing on electron-phonon interactions and transition temperature dependencies.

Contribution

It develops a parameter-free approach combining phonon spectra and Kohn-Sham-Bogoliubov-de Gennes equations for superconducting systems.

Findings

Transition temperature varies with slab thickness.

Inverse proximity effect observed in heterostructures.

Method successfully applied to niobium-based systems.

Abstract

We present a fully first-principles method for superconducting thin films. The layer dependent phonon spectrum is calculated to determine the layer dependence of the electron-phonon coupling for such systems, which is coupled to the Kohn-Sham-Bogoliubov-de Gennes equations, and it is solved in a parameter free way. The theory is then applied to different surface facets of niobium slabs and to niobium-gold heterostructures. We investigate the dependence of the transition temperature on the thickness of the slabs and the inverse proximity effect observed in thin superconducting heterostructures.